I've been thinking, based on discussion in the thread on spreading the word on Rocket Mass heaters, that widespread adoption of rocket heaters requires a different design. I'd like to lay out my hypothesis and hope people will critique it.
1. The majority (likely 95+%) of the population would never build or install a RMH. They are scared of building a stove, of carbon monoxide, of the mass, of doing something like that in their house/trailer/apartment, etc. There are struggles with insurance and codes. and there is not enough skilled labor to hire it out. Many people have commented on this. It is just a fact, advertising or education won't fix this.
2. Widespread adoptions of sustainable wood heating requires something that is:
a. Off the shelf
b. standardized (UL listed, and meets code)
c. Easy to install in a wide range of dwellings with minimal modifications
d. Affordable
e. maximize percent of usable heat in the dwelling for a given fuel input
f. Very clean burn to not have localized air quality issues.
3. The traditional woods stove achieves a, b, and c. but struggles with d, e, and f. You either burn fast, which produces more BTUs than needed for a brief period and pumps lots of heat and pollution out the chimney. Or you damper it down which creates condensation of creosote in the chimney and eventual chimney fires. One solution to minimize condensation and or risk to the dwelling from overheating the chimney is triple layer insulated chimney which is very expensive.
4. The Traditional RMH design achieves e and f by introducing a high temperature burn riser which burns nearly all the fuel. This allows the chimney to be cooler without a creosote problem, which then allows depositing a greater fraction of the heat inside the house, and also gives less pollution in the output.
5. However the RMH achieves this high temperature burn by running fast and hot (wide open) on stick or cord wood creating a high BTU output for a short period. This requires an efficient way to store that heat energy for use over an extended period, which is solved by a custom thermal mass and custom install. If you are a homesteader RMH pioneer a, b, and c are less a factor and you achieve d (affordability) by doing it yourself. But for the average population, that needs to hire it out, requiring the thermal mass pushes things into a custom space where factors a, b, c, and d preclude widespread adoption.
6. If you can achieve the wide open hot burn but yet have a long burn at a lower BTU output then the large thermal mass is not needed. I think the candidate design for a achieving this in an off the shelf system is a pellet rocket heater, with the insulated riser to achieve the high temp and clean burn, a small burn chamber and riser and a low pellet feed rate to give a low BTU output, and a design to extract most of the heat before going up the exhaust pipe so it can be both small and cool (cheap).
has anyone tried this? If they have I haven't been able to find it.
The liberator has a pellet adaptor, but it is sized for a higher BTU output and nominally still needs a thermal mass. The Wiseways is designed for a use without the thermal mass, but it doesn't have an insulated heat riser to give the "rocket" with a hot efficient burn so you send more heat/pollution up the exhaust pipe.
I'm thinking the right design can be similar to the wood stove in price <$1000, but much cheaper on the chimney cost.
For people in rural areas it is better having something that takes sticks and cord wood, but for urban dwellers, the logistics will favor getting pellet fuel through local stores.
